This invention relates generally to filling a container with material, and more particularly concerns a fill nozzle for controlling the flow of powders such as toner from a fill tube to a toner container.
Currently when filling powders, for example toners into toner containers, toner is transported from the toner supply hopper into the container by a rotating auger. The auger is a spiral shaped mechanical part which pushes particles of toner inside a fill tube by direct mechanical contact. The nature of this mechanical contact process creates substantial limitations on accuracy and productivity of the toner filling operation. The speed of the toner movement in the fill tube is proportional to the speed of rotation of the auger and is limited by heat release due to auger/toner friction. High auger speed will cause the toner to melt, particularly for low melt toner such as disclosed in U.S. Pat. No. 5,227,460 to Mahabadi et al. the relevant portions thereof incorporated herein by reference.
To provide for productive efficient toner containers, typically, the rotating augers used to transport the toner from hoppers are relatively large. The large augers provide for high volume toner flow and thus improve productivity in a fill line. When utilizing such fill lines for small, low cost copiers and printers, difficulties occur in that the openings in the toner containers utilizing such small copiers and printers include a small toner fill opening that may have an irregular shape and have a fill opening that is not centrally located in the container. Problems are thus associated with fitting the large filling tubes and augers with the small toner fill openings.
Problems with filling containers with toner are exacerbated in that the small low cost copies are produced in higher quantities necessitating very efficient toner filling operations.
Problems with efficient toner filling are also apparent in small and medium cost multi-colored highlight or full color printers and copiers. The toner containers for color toner typically are smaller than those for black toner and also more typically have an irregular shape. Further, color toners have been developed with smaller particle size of for example 7 microns or less. These smaller toners are more difficult to flow through toner hoppers and are more difficult to be translated along augers.
Toner containers for small low cost printers and copiers typically have a small opening into which the toner is to be added. Furthermore, the toner containers often have irregular shapes to conform to the allotted space within the copying machine. Therefore it becomes difficult to fill the toner container because of the small tube required to fit into the small toner container opening and secondly for all the toner within the container to completely fill the remote portions of the container before the container overflows.
The problems associated with controlling the filling of toner containers are due primarily to the properties of the toner. Toner is the image-forming material in a developer which when deposited by the field of an electrostatic charge becomes the visible record. There are two different types of developing systems known as onecomponent and two-component systems.
In one-component developing systems, the developer material is toner made of particles of magnetic material, usually iron, embedded in a black plastic resin. The iron enables the toner to be magnetically charged. In two-component systems, the developer material is comprised of toner which consists of small polymer or resin particles and a color agent, and carrier which consists of roughly spherical particles or beads usually made of steel. An electrostatic charge between the toner and the carrier bead causes the toner to cling to the carrier in the development process. Control of the flow of these small, abrasive and easily charged particles is very difficult.
The one-component and two-component systems utilize toner that is very difficult to flow. This is particularly true of the toner used in two component systems, but also for toner for single component systems. The toner tends to cake and bridge within the hopper. This limits the flow of toner through the small tubes which are required for addition of the toner through the opening of the toner container. Also, this tendency to cake and bridge may cause air gaps to form in the container resulting in partial filling of the container.
Attempts to improve the flow of toner have also included the use of an external vibrating device to loosen the toner within the hopper. These vibrators are energy intensive, costly and not entirely effective and consistent. Furthermore, they tend to cause the toner to cloud causing dirt to accumulate around the filling operation.
Also, difficulties have occurred in quickly starting and stopping the flow of toner from the hopper when filling the container with toner in a high speed production filling operation. An electromagnetic toner valve has been developed as described in U.S. patent applications, Ser. Nos. 08/540,993 and 08/690,412, assigned to the same assignee as this application, the relevant portions incorporated herein by reference. The electromagnetic valve is limited for use with magnetizable toner such as that described for use with one component development systems.
Attempts have been made to fill toner containers having small toner fill openings by utilizing adapters positioned on the end of the toner filling auger which has an inlet corresponding to the size of the auger and an outlet corresponding to the opening in the toner container. Clogging with toner, particularly when attempting to increase toner flow rates and when utilizing toners with smaller particle size, for example, color toners having a particle size of 7 microns or less, has been found to be a perplexing problem. The adapters that are fitted to the augers, thus, tend to clog with toner. The flow rates through such adapters is unacceptably low.
Further, the use of these adapters may create problems with maintaining a clean atmosphere free of toner dust at the filling operation.
The following disclosures may be relevant to various aspects of the present invention: